1. Field of the Invention
The present invention relates to a mobile terminal device (also referred to simply as ‘terminal’ hereinbelow) that constitutes an adhoc network, a control method, and a mobile communication system.
Further, in this specification, ‘transmit’ signifies that a mobile terminal device transmits packets to an adjacent mobile terminal device as the transmission source of the packets and ‘transfer’ signifies that a mobile terminal device transfers a packet received from another mobile terminal device to an adjacent mobile terminal device.
2. Related Background Art
In routing protocol in an adhoc network (a so-called ‘pure adhoc network’) configured only by a plurality of mobile terminal devices without the requirement for equipment constituting an infrastructure for the mobile communication network, routing control based on flooding which delivers control packets of link information and so forth to all of the nodes in the network is carried out. Hence, when the number of terminals increases, control packets flow in large volumes in the network and the communication bandwidth is compressed. As a method for reducing this problem, OLSR (Optimized Link State Routing) uses an MPR (MultiPoint Relay) set (See document ‘T. Clausen and P. Jacquet et al., Project Hipercom, “Optimized Link State Routing Protocol (OLSR)”, RFC3626, <URL:www.ietf.org/rfc/rfc3626.txt>’). In OLSR, each terminal selects a minimum multipoint relay (MPR) that is required in order to deliver packets to all the terminals connected two hops from the terminal itself, from the terminals connected one hop from the terminal itself. When a terminal floods the whole network with packets, the packets are relayed only by the terminals which have been selected as the MPR of the terminal that transmitted the packets. As a result, it is possible to deliver packets to all the terminals two hops from the terminal that transmitted the packets originally. In addition, the terminals selected as the MPR relay the packets, and the packets are relayed again and again. Consequently the packets are delivered to the whole network. Thus, in OLSR, by performing flooding efficiently, routing with a small overhead is implemented.